Update from chromium https://crrev.com/301725/

net/base/network_change_notifier_linux.cc

Index: net/base/network_change_notifier_linux.cc
diff --git a/net/base/network_change_notifier_linux.cc b/net/base/network_change_notifier_linux.cc
index b10f8a8e640e140fe49b62210d3e404cc239a52e..f77025a33d8904750a0d3e227c59f7086305c09b 100644
--- a/net/base/network_change_notifier_linux.cc
+++ b/net/base/network_change_notifier_linux.cc
@@ -15,7 +15,7 @@ namespace net {
 class NetworkChangeNotifierLinux::Thread : public base::Thread {
  public:
   Thread();
-  virtual ~Thread();
+  ~Thread() override;
 
   // Plumbing for NetworkChangeNotifier::GetCurrentConnectionType.
   // Safe to call from any thread.
@@ -29,8 +29,8 @@ class NetworkChangeNotifierLinux::Thread : public base::Thread {
 
  protected:
   // base::Thread
-  virtual void Init() override;
-  virtual void CleanUp() override;
+  void Init() override;
+  void CleanUp() override;
 
  private:
   scoped_ptr<DnsConfigService> dns_config_service_;